Commercial heating system design in Brighton and Sussex, built around the building rather than the catalogue

The most common instruction we are given is to replace what is there with the same size of new plant. It is the quickest way to specify a job and it is usually wrong, for two reasons that compound each other.

The first is that the original was very often oversized. Older commercial systems were designed with generous margins on top of already cautious figures, so plant that has been running for twenty years may never have been matched to the building at all. The second is that the building has changed since. Windows, roofs, insulation, occupancy patterns and use all move, and almost every change over the last two decades has moved the heat loss down.

An oversized boiler does not simply cost more to buy. It short-cycles, which wears the plant, wastes gas and makes the building harder to control. Sizing against a real heat-loss calculation frequently lets us replace a single large unit with a modular cascade of smaller ones for a similar capital figure, and the building then gets better part-load efficiency and a system that keeps running when one module needs attention.

Where a consultant has already produced a specification we install to it, and we flag anything the survey shows the drawings did not anticipate rather than discovering it halfway through.

Any commercial design should answer a blunt question: what happens to this building when one part of the plant stops working. On a Tuesday in February the answer matters more than the efficiency figure on the brochure.

Modular cascades are usually the answer. Several smaller boilers sequenced together give better efficiency across the part-load conditions a building spends most of its life in, and they mean a single fault reduces capacity rather than removing it. For a care home, a school or a managed block, that difference is the whole design.

Resilience also shapes the replacement programme. Where the plant allows, we phase a changeover so one boiler stays live throughout, and where it does not we design in temporary heat for the window. Care home plant rooms have been stripped out and rebuilt in November with residents keeping heat and hot water the whole time, and a Tesco Extra plant room was upgraded while the store kept trading. On a school, the work is programmed into a holiday so the building opens with the heating on.

A well-sized system with a poor controls strategy will still waste money and still generate complaints. Controls are where a design either responds to how the building is used or fights it.

We design the sequencing of the plant, the zoning of the building, weather compensation, time and temperature strategy, and the interface with an existing building management system where one is in place. On multi-tenant and mixed-use buildings that usually means designing for parts of the building running on completely different schedules without the plant cycling itself to death serving whichever zone is awake.

Where there is a BMS we integrate with it rather than around it, and where there is not we specify controls a facilities team can actually operate, then leave the strategy written down. A controls scheme that only its designer understands is a fault waiting for the day that person is unavailable.

The deliverable is a set of documents your consultant, main contractor or procurement team can tender, build and sign off from, produced to the same standard whether we install the job or not.

Where we also carry out the installation, the design documents continue into commissioning: the system is balanced and commissioned against the design figures, and the handover pack records what was actually installed rather than what was originally drawn. On gas work, certification is issued on completion for your compliance file.

Accreditations are only useful if you know what they cover. These are the ones we hold and what each means to the person responsible for the building. Certificates and insurance documents are available on request.

Some of the design work we do is design-and-build, where we survey, calculate, specify, install and commission. The rest is installing to a consultant's specification, and we are comfortable in either position.

Where a specification already exists we price it as drawn, then raise anything the survey contradicts before the order rather than after. Where a main contractor needs a specialist mechanical subcontractor we come with CHAS, Gas Safe, REFCOM and MCS, and provide RAMS and reporting your client can see. Where an FM team is inheriting the system, we write the controls strategy and the handover so it can be operated by the people who will actually operate it.

Our hours are Monday to Friday, 08:00 to 17:30. We do not offer an out-of-hours or weekend call-out service, and we would rather say so before a contract is signed than have a building manager discover it on a Sunday.

We work from central Brighton, which puts the whole of East and West Sussex within a normal working day. That covers Brighton and Hove, Lewes, Newhaven, Seaford, Eastbourne, Bexhill and Hastings along the east coast, Shoreham-by-Sea, Worthing, Littlehampton, Bognor Regis and Chichester to the west, and inland through Hassocks, Burgess Hill, Haywards Heath, Horsham, Crawley and East Grinstead.

For design and installation projects we also work across London, Surrey, Kent and Hampshire. Completed work includes commercial gas purging and testing at an airport, four boilers serving more than 200 apartments in east London, and plant room and boiler projects at Tesco sites and a hospital.